This invention relates to a solid-state laser device for use in welding, perforation, laser annealing, or the like.
A recent requirement for a solid-state laser device of the type described is to augment power of an output laser beam emitted from the laser device. For this purpose, a conventional solid-state laser device comprises a laser oscillator for oscillating an oscillation laser beam and a laser amplifier coupled to the laser oscillator to amplify the oscillation laser beam into the output laser beam. In each of the laser oscillator and the laser amplifier, a laser rod is optically excited or energized by flash lamp or lamps within a reflector having an elliptic cylinder space.
The conventional solid-state laser device becomes bulky in size because the laser rod of the laser amplifier should be spaced apart from that of the laser oscillator with optical axes of both laser rods matched with each other. Inasmuch as the laser rods are individually energized by the flash lamps in the laser oscillator and in the laser amplifier, the number of the flash lamps inevitably increases in the laser device. This results in a large electric power consumption.
In addition, use of the laser rod in the laser amplifier makes it difficult to augment the output laser beam. This is because a thermal distortion becomes serious and crucial and ultimately brings the laser rod to destruction when the laser amplifier has a high gain. The thermal distortion also brings about a reduction of efficiency of the laser rod.
In U.S. Pat. No. 3,633,126 by W. S. Martin et al, an elongated active laser medium is proposed which has a pair of principal surfaces parallel to each other and which is rectangular in cross section. Such a rectangular laser medium may be called a slab-type of a laser medium and may serve to lower the thermal distortion and to thereby generate an output laser beam of high power.
The laser medium of the slab-type may be laid in the laser amplifier in place of the laser rod and may optically be coupled to the laser oscillator to form a high power laser device. However, such a high power laser device inevitably becomes large in size as long as the laser oscillator is spaced apart from the laser amplifier.